branch!!

3 files changed, 29 insertions, 3 deletions

diff --git a/jefs.fs b/jefs.fs
index 345d31a..38c2c5f 100644
--- a/jefs.fs
+++ b/jefs.fs
@@ -1,6 +1,12 @@
+: begin here @ ; immediate
+: again branch here @ 4 + - d, ; immediate
+
 : / /mod swap drop ;
 : mod /mod drop ;
 
 : syswrite ( u c-addr fd -- n ) 1 syscall3 ;
 : say ( c-addr u -- ) swap 1 syswrite drop ;
+\ : saying begin TESTSTR say again ;
+HEREDUMP
+\ saying bye
 TESTSTR say bye
diff --git a/jefs.s b/jefs.s
index 71854b4..05598a0 100644
--- a/jefs.s
+++ b/jefs.s
@@ -117,6 +117,14 @@ defword ",", comma, 0
 	mov qword [here], r12
 	ret
 
+defword "d,", d_comma, 0
+	pspop r11
+	mov r12, [here]
+	mov dword [r12], r11d
+	add r12, 4
+	mov qword [here], r12
+	ret
+
 defword "w,", w_comma, 0
 	pspop r11
 	mov r12, [here]
@@ -543,8 +551,8 @@ defword "+", plus, 0
 defword "-", minus, 0
 	pspop r11
 	pspop r12
-	sub r11, r12
-	pspush r11
+	sub r12, r11
+	pspush r12
 	ret
 
 defword "*", _times, 0
@@ -616,6 +624,18 @@ defword "immediate", immediate, 0
 	mov byte [r12], r13b
 	ret
 
+; e9 [00 00 00 00] relative 32 bit immediate, relative to *instruction after jump*!
+; note: the dummy value must be provided *by the calling word*
+defword "branch", branch, 0
+	mov r12, [here]
+	mov byte [r12], 0xe9
+	inc r12
+	mov qword [here], r12
+	ret
+
+; defword "0branch", zerobranch, 0
+; 	ret
+
 ; TEMPORARY HORRIBLE DEBUGGING BULLSHIT {{{
 ; debugging word; outputs raw bytes so needs to be piped through `x(x)d`
 ; terrible and awful
diff --git a/readme.md b/readme.md
index 252e909..dc3d234 100644
--- a/readme.md
+++ b/readme.md
@@ -20,7 +20,7 @@ the dictionary follows a fairly standard format.
 ## the one reserved register
 
 the working stack pointer is `r14`.
-the other registers are used as general purpose registers
+the other registers are used as general purpose registers;
 `r11` in particular is the standard register used in
 compiling calls.